High-current high-voltage switch with incisor electrode

ABSTRACT

A rapid-action switch, especially for the switching of high voltages and currents in plasma physics, magnetohydrodynamics and like technologies in which an explosive force is produced by discharge through a consumable electrode within a U-shaped aluminum body separated from a switching electrode bearing a sharp edge and sandwiched between this electrode and a counterelectrode constituting an anvil. An insulating layer between the proximal leg of the aluminum U and the sharp edge is pierced as this leg is deformed by the exposure to bring the edge into contact with the U and thereby close the circuit.

United States Patent Dokopoulos Feb. 8, 1972 [54] HIGH-CURRENT HIGH-VOLTAGE 3,238,321 4/1966 Lawwill et a1... ...200/61.08 SWITCH WITH INCISQR ELECTRODE 3,269,987 8/1966 Alston et al ...200/6l.08 3,509,508 4/1970 Kraemer et al. ZOO/61.08 [72] Inventor: Petros Dokopoulos, Juehch, Germany Primary Examiner-Robert K. Schaefer [73] Assignee. Kernforschungsanlage Juelich Assistant Examiner M. Ginsburg mil beschrankter Haftung, Juehch, Ger- Altomeyl(arl E. Ross many [22} Filed: Oct. 21, 1969 [57] ABSTRACT [21 App] No; 868,192 A rapid-action switch, especially for the switching of high voltages and currents in plasma physics, magnetohydrodynamics and like technologies in which an explosive force is produced [30] Foreign Application Priority D by discharge through a consumable electrode within a U- shaped aluminum body separated from a switching electrode Oct. 23, 1968 Germany ..P 18 04 609.8 bearing a Sharp edge and Sandwiched between this electrode and a counterelectrode constituting an anvil. An insulating U-S. Cl. layer between the p i g of the aluminum U and the [51 1 f r 39/00 sharp edge is pierced as this leg is deformed by the exposure to [58] Fleld of Search the edge in ontact the U and thereby close the circuit. [56] References Cited 14 Claims, 8 Drawing Figures UNITED STATES PATENTS 3,117,194 1/1964 Stresau ..200/61.08

I? 23 Transformer -(V Oil J! 2 3 5 I Z5 SQ I l l T i i L- PATENTEUFEB 8 I972 SHEET 1 [1F 4 I N V E N TO R Pefros Dokopoulos PATENTEDFEB a 1912 SHEET 2 OF 4 IN E N TORI Pe fro; Dokopou/os Attorney PMENTEUFEB 8l972 3.641.289

sum 3 0F 4 INVENTOR. Pefros Dokopou/os Attorney PATENTEB FEB 8 m2 SHEET a [1F 4 FIGS v v i i 1 mlrL IMOWOJ :ZWW "L /IRL Perros Dokopoulos INVEA I'OR Attorney HIGH-CURRENT HIGH-VOLTAGE SWITCH WITH INCISOR ELECTRODE My present invention relates to a rapid-action switch for the control of high voltages and high currents and, more particularly, to a switching arrangement for the rapid closure of an electrical circuit capable of withstanding voltages above 1,000 volts (v.) and of conducting currents of above 1,000 amperes (amp.).

Switch arrangements with the aforedescribed requirements have been found necessary in the technologies of plasma physics, magnetohydrodynamics and the like for the control of magnetic or electrical fields or the production of these fields, for the creation of electrical discharges and, therefore, for the production, control or enclosure of ionized gases at highpotential energies.

It has been proposed in the art to provide a switch arrangement for such systems in which a pair of electrodes extending generally parallel by spaced-apart relationship while an aluminum member is disposed between these electrodes and is provided with arms which may be explosively spread to cause an edge, point or like formation on one of the electrodes to pierce an insulating layer and thereby create a metallic electrical connection between the electrode bearing this formation and the counterelectrode through the aluminum body. The aluminum body is deformed by the exposure which may be initiated by the use of a fusible metal foil through which an electric current is passed to disintegrate the fusible strip.

In dealing with rapid-action switches for the control of highcurrent installations and especially installations involved in the study or utilization of the technology of plasma physics, several requirements must be considered. Firstly, the switch must have a relatively short operating time, i.e., the period between incipient switch closure and maximum switch closure must be as small as possible; secondly, the switch-closing action must occur with a minimum of spread of the switching time from operation to operation. Thirdly, the switch must have low inductivity, extremely small resistance in the closedcircuit condition and high resistance to breakdown at elevated potentials (high-breakdown voltage), as well as resistance to deterioration at high-current flows. The switch must also have a high resistance in the open-circuit condition.

In considering these requirements in the light of prior art switching arrangements, it is found that high-current switches in which conduction is created through an electric are are disadvantageous whether the arc is maintained through a gas or dielectric-filled gap since the arc path usually has excessively high resistance and causes relatively elevated ohmic losses, thereby limiting the current fiow.

In still other arrangements in which mechanically operated devices bring the electrodes together, it is found that the switch-closure time is relatively high and even the use of chemical explosives to drive the electrodes together has been found to require greater switch-closing times than is desired for the applications indicated.

With prior art switch arrangements of the character set forth, i.e., using a pair of electrodes, one of which is provided with a piercing formation, a distortable aluminum body between the electrodes, an insulating layer adapted to be pierced by the formation and sandwiched between the aluminum body and the formation, and a system for explosively deforming the aluminum body, it is found that switching times of 9:t0.5 microseconds can be obtained to metallic contact; such an arrangement is described by Edwin L. Kemp, The Design of Seyllac, A l-Meter THETA-PINCI-I MACHINE, Los Alamos Scientific Laboratory, Report 59, presented on the fifth Symposium on Fusion Technology, July 1968, Oxford, U.l(. Even this switching time has been found to be excessive for many purposes and the switch has undesirable tendencies to create electric arcs.

Another disadvantage is the relatively large inductivity and short life span of the switch, the latter resulting from the fact that the individual switch parts are consumed relatively rapidly.

It is, therefore, the principal object of the present invention to provide an improved rapid-action switch with reduced switching time, low inductivity, high current-carrying capacity, low switching-time spread or variation and relatively low cost and long operating life.

Another object of this invention is to provide an improved rapid-action switch, especially for use in plasma physics nd magnetohydrodynamics technologies which avoids the aforementioned disadvantages and is capable of switching electric currents of 1,000 amperes or more and of withstanding opencircuit voltages of 1,000 volts or more.

These objects and others which will become apparent hereinafter are attained in accordance with the present invention in a switch of the type described immediately above but modified with respect to the metal-foil electrodes adapted to generate the explosion or explosive force deforming the aluminum body.

A rapid-action switch, according to the present invention, thus comprises a pair of spaced-apart electrodes, a U-shaped aluminum body disposed between these electrodes such that the arms of the U extend parallel to the electrodes, a sharpedged membrane-piercing formation on one of the electrodes, an insulating film, foil, layer, coating or other membranous or sheetlike member insulating the corresponding arm of the U from the piercing electrode and, between the arms of the U, one or more explosively disintegratable metallic foils energized at a voltage with a higher potential than that across the electrodes and of a critical configuration as set forth below.

Advantageously, two distinct metallic foils or interconnected foil portions extend toward one another in generally coplanar relationship at identical distances from the legs or arms of the U and may contact the latter at mutually confronting inner ends. An important feature of this invention resides in providing the explosion-producing foils or foil portions of such configuration that they are of monotonically increasing cross section outwardly from one another and in accordance with a monotonic function toward the connection to the triggering-pulse source which is connected to the respective electrode outwardly of the contact of the electrode with the aluminum U. Preferably, the metallic foils or foil portions are flat bands lying in a plane parallel to the arms of the U and widening monotonically outwardly from one another from a relatively narrow region to a relatively wide region with a cross-sectional area ratio of the order of 1:10.

A configuration of the foils of this type appears to ensure that the explosion occurs at the regions of closest approach of the metal foils or foil portions and at the'narrow end of each such foil or foil portion and is propagated outwardly from a perpendicular to the central axis of both electrodes at the axis of symmetry of the foil-electrode system. While applicant does not wish to be bound by any theory as to the operation of his improved switch, it appears that this relationship provides a substantially reduced switch time by comparison with earlier systems and arrangements in which the foils are of uniform or different cross section and moreover the variance of the switch times or spread in the performance of the switch in terms of the switch time is reduced markedly. Furthermore, it has been found that still greater improvement in the switching time and spread is obtainable when the explosion-producing metallic foil is composed of aluminum or aluminum alloys containing a preponderance of aluminum. The piercing and counterelectrodes are best composed of copper-beryllium alloy and may be coated with voltage-controlling layers of metal orsemiconductor to increase the breakdown potential of the system.

Still another feature of this invention resides in the provision between the metal foil and the arm of the U juxtaposed with the nonpiercing or anvil electrode, of a plate of low deformability, high structural and compressive strength and high bending strength such that, upon explosion of the metal foil, it has little tendency to deform. This plate, preferably of steel, appears to ensure concentration of the explosive force at the deformable arm of the U, thereby further reducing switching time and the spread of switching times with switch arrangements of this character.

To prevent inadvertent or undesired opening of the contacts, for example under the force of magnetic fields produced on switch closure or corresponding forces or to restrict the tendency of the switch to open, Iprefer to provide in a piercing electrode in the region of the piercing edge, one or more inwardly widening grooves whose mouths are smaller than the floors and which widening inwardly whereby the deformable arm of the U, once driven by the explosion force into the groove, will be effectively locked in contact with the piercing electrode.

It has also been found to be desirable, in this connection, to provide within the groove a system of mutually orthogonal prismatic bars or ridges whereby above the narrowest region of the explosion-producing metallic foil the bar or ridge corresponds to the width of the foil and runs parallel thereto. In this case it is advantageous to so arrange the prismatic bars or ridges in a cruciform configuration that the lengths of the bars each correspond to the dimension of the foil electrodes in the direction of elongation of the bars or ridges electrode. Thus, even if the foil electrodes are offset slightly from their desired positions between the arms of the U, there will be no adverse effect upon the switching time.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a cross-sectional view transverse to the longitudinal direction of a switch embodying the present invention;

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1;

FIG. 3 is a cross section taken generally along the line III- III of FIG. 1 with the explosion-producing foil somewhat modified in accordance with an aspect of the present invention;

FIG. 3A is a detail view of the electrode arrangement of FIGS. 1 and 2, viewed from above along a section line corresponding to that shown at IIIIII;

FIG. 4 is a longitudinal cross section through another switch arrangement according to the present invention;

FIG. 5 is a view taken along the line VV of FIG. 2 illustrating the upper main electrode from below;

FIG. 6 is a detail view of another embodiment of the present invention; and

FIG. 7 is a detail view illustrating the contact between the upper electrode and the'aluminum U of the switch of FIGS. 1 and 2 upon piercing of the insulating layer normally separating same.

In FIGS. 1 and 2, I have shown a rapid-action switch in accordance with the present invention which comprises an upper principal electrode 1 of copper-beryllium alloy which may hereinafter be referred to as an incisor electrode. The electrode 1 can be pressed downwardly by a piston 19a of a fluid-responsive cylinder 19b to exert the desired precompression upon the electrode assembly. The electrode 1 is spacedly juxtaposed with the other principal electrode 2 of copperberyllium alloy (anvil electrode), the entire assembly being mounted, if desired, in a vessel 20. The vessel 20 may be a pressuretight receptacle which may be supplied with, for example, a breakdown-limiting gas, e.g., sulfur hexafluoride (SP at a pressure up to about 16 atmospheres gauge and at a superatmospheric level. The introduction of a gas of this type at superatmospheric pressure has been found to increase the breakdown voltage of rapid-action switches of this type. The electrodes may be coated or lined along their surfaces confronting an aluminum U 9, with a potential controlling layer or film of metal or semiconductor which establishes the voltagebreakdown level of the switch.

The vessel 20 may be filled with an electrically insulating oil, e.g., transformer oil, or a low-conductivity electrolyte. When sulfur hexafluoride is used, the gas may be introduced from a tank 21 via a valve 22 and maintained at the aforedescribed superatmospheric pressure as indicated by the gauge 23. The transformer oil can be introduced from the tank 24 via the pump 25.

In the embodiment illustrated in the drawing, the rapid-action switch is inserted in an oscillation circuit for plasma installations, the circuit including a pair of bus bars 3 and 4 respectively connected to the load inductivity 6 of the circuit as shown in FIG. 1. The energy source is a condenser bank represented at 5 in which a switch 5a may apply the capacitance 5b across the inductor 6. Thus the electrode 1 and the electrode 2 are so connected with the bus bars 3 and 4 as to form with the energy-storage bank 5 and the load inductivity 6 the oscillation circuit. Upon short circuiting of the electrodes 1 and 2 at the first current maximum after the switching of capacitor bank 5 into the circuit, I am able to reduce the decay of the energy stored in the inductance 6 and prevent reversal dissipation of energy in the condenser bank 5. If the inductance 6 is then used to generate a magnetic field for the control, activation or stabilization of a magnetic field affecting a plasma, this magnetic field will have a short rise time and a large reversal half-life (see the cited publication). Furthermore, the condenser battery 5 which may be sensitive to rapid reversal of polarity, is protected.

The bus bars 3 and 4 are relatively movable to clamp an insulating foil 14 between their confronting faces 30 and 4a flanking openings 3b and 4b in which the principal electrodes 1 and 2 are seated. To this end, the bus bar 4 may rest upon a support of the hydraulic press, the ram of which is constituted by the piston-and-cylinder arrangement 19a, 19b. A pair of inwardly projecting longitudinally extending ledges 4c reach toward one another at the bottom of the opening 4b and constitute rails carrying outwardly extending longitudinal flange 2a of the anvil electrode 2 which thus rests upon these ledges and can be inserted or removed by an endwise displacement of the electrode 2 in the direction perpendicular to the plane of the paper in FIG. 1.

The other principal electrode 1 is likewise provided with a pair of flanges la which project laterally along opposite upper longitudinal edges of the electrode and overlie the bus bar 3v adjacent the opening 3b so that a vertical pressure applied in the direction of arrow A by the hydraulic piston-and-cyiinder arrangement 19a, 19b urges the electrode 1 downwardly against the electrode pack while the anvil electrode 2 supports the pack.

The upper of incisor electrode 1 is formed along theunderside of its massive central body lb (flanked by the flanges 1a with downwardly tapering wedge-shaped prismatic ridges 7 and 8 constituting incisor blades adapted to penetrate the insulating foil or layer 14 and establish an electrical connection with the electrode pack, as will be apparent hereinafter. The

ridges 7 and 8 extend in the direction of the anvil electrode 2 and are wedge-shaped i.e., half the configuration of triangular prisms) while lying at right angles to one another in a cruciform configuration as is described in greater detail below. The sharp edges 7a and 8a of these ledges can be seen in FIGS. 1 and 5.

The electrode pack adapted to initiate switch closure, according to this invention, includes a U-shaped aluminum plate 9 of aluminum or an aluminum alloy in which the aluminum component predominates. As will be apparent from FIGS. 1 and 2, the U-shaped aluminum channel or yoke 9 comprises a pair of mutually spaced parallel flat arms or legs 9a and 9b, the former lying in surface contact with the horizontal flat face 2b of the anvil electrode 2 and thereby establishing electrical connection therewith. The legs 9a and 9b and their free ends are oriented to the right in FIG. 1 but are connected unitarily and integrally (i.e., in one piece) by a bight 9c lying at the lefthand side of FIG. 1 and extending in the longitudinal direction of the assembly, i.e., parallel to the electrodes 1 and 2 as shown in FIG. 2 and perpendicular to the plane of the paper as illustrated in FIG. 1. The upper or deformable arm or leg 9b of the U immediately underlies the foil 14 below the bottom face 10 of the body of the electrode 1 so that prior to activation of the switch, the foil 14 is held tightly against the upper leg 9b of the U.

The mutually confronting inner faces of the legs or arms 9a and 9b of the U are provided with insulating layers which may be electrically insulating synthetic resin, rubber or the like, but preferably is a high compressive strength insulator, such as mica, a phenol-formaldehyde or melamine resin plate or laminate. Alternatively, the layers 10 may be provided as coatings or laminated layers upon the activation electrode 11 which is sandwiched between them. In FIGS. 1, 2 and 3A, there is shown a preferred embodiment of this invention in which the explosions producing electrodes 11 are two in number and are constituted as aluminum foils or a foil of an aluminum alloy containing a preponderance of aluminum. As will be evident from FIGS. 2 and 3A, the foils 11 have narrow or slender inner extremities 11a reaching toward one another symmetrically with respect to a median plane P perpendicular to the major axis B of these electrodes, but spaced apart by a narrow gap 11b. In the embodiment represented in FIGS. 1 and 3A, the narrow extremities are turned upwardly and extend through an opening 10a provided in the upper coating 10 to contact the underside of the upper aluminum leg 9b, preferably at a contact insert 9d pressed into the aluminum U and of high electrical conductivity (e.g., a silver alloy). This ensures an effective electrical connection between the narrow ends of the electrode 11 and the aluminum U. From FIG. 2, it is also clear that, apart from members 10 and aside from the region at which the tips 11a make electrical contact with the aluminum U 9, the foil may be coated at 11c with a synthetic resin or rubber of electrically insulating character. In other words, the electrodes 11 bear at their narrow inner edge upon the aluminum U; at their wider edges extending oppositely from one another and projecting beyond the channel 9e formed by the U, the aluminum electrodes 11 may be connected via leads 11d with a high-voltage terminal of a pulse source 12. The pulse source 12 may be condenser batteries as shown diagrammatically in FIG. 2 in series with respective resistors, the condenser batteries having a low capacity and small size by comparison with the condenser bank 5.

Between the bottom leg 9a of the U and the metal foils 11, I provide a metal plate 13 of high bending and compressive strength, preferably of steel. To insulate the piercing electrode 1 of the switch relative to the U-shaped aluminum member 9 which rests in direct contact with the counterelectrode 2, there is provided the foil 14 preferably of a synthetic resin such as polyethylene or a polyester which is pierced by the sharp edges of the piercing electrode 1 to effect metallic contact between the upper leg 9b of member 9 and electrode 1 upon triggering of an explosive force by the foils 11.

As can best be seen from FIG. 3 and FIG. 3A, the metal foils 11 have a monotonically increasing cross section from a perpendicular to a central axis B of the metal foils 11 with a ratio of the cross section from the narrowest to the widest part of substantially 1:10. The wider end of the electrode 11 is connected to a high-voltage terminal of the trigger-pulse source 12 associated with the respective electrode 11 so that the explosion begins at the center of the switch between the electrodes l and 2 and widening outwardly in a propagation mode substantially in accordance with the configuration of the electrodes. As a result, the switching time (i.e., the time from trig gering to deformation of the upper leg 9b of the aluminum U,into metallic contact with the switching electrode 1 is held extremely low and without significant spread. When the ratio between the smallest and the largest cross sections of the metallic foil 11 is about 1:10, the explosion results in a large contact surface between the upper leg 9b of the aluminum U and the switch electrode 1.

The metal foils 11 are so arranged between the deformable leg of the aluminum member 9 and the deformation-resisting metallic plate 13 that practically no air or gas blast can occur in the region of these electrodes, thereby further assuring relatively short switching time, minimum arc development at maximum contact surface upon switch closure. Thus, it has been found to be advantageous to shape the deformation-resistant metallic plate 13, as shown in FIG. 4 such that no air passage can be formed around the metal foil 11. To this end, the plate 13 cooperates with a further plate 15 overlying same and composed of metal or a synthetic resin which holds the bottom-insulating layer 10 against the underside of the foils 11. At the relatively large-section ends of the electrodes 11, I provide relatively thick metal foils 16 which are clamped against the foils 11 between the insulating layers 10 and serve as terminals connected with the trigger-pulse source.

As can be ascertained from the drawing, the ridges 7 and 8 of the piercing electrode 1 are of generally prismatic configuration and lie in mutually intersecting relationship of cruciform configuration above the metal foils 11 so that the metal foils l l have their narrowest dimensions below the edges 7a or ridges 7 and their largest section below the edge 8a of ridge 8. The cruciform relationship is apparent from FIG. 5 in which ridges 7 and 8 are not or less dependent from one another within the channel 17 and ridges 8 terminate at ridges 7.

A modification of this structure is shown in FIG. 6 in which the ridge 108 has its cutting edge 108a terminating at a junction 108 with the cutting edge 107a of aridge 107 intersecting the ridge 108 such that a ridge portion 108" with cutting edge 108a extends beyond the ridge 107. Here, too, the cutting arrangement is provided in a groove as represented at 17 (here shown in dot-dash lines. In both of these arrangements, it is found that deviations of the positions of the metal foils 1 1 from their desired positions vis-a-vis the piercing elec trode body up to several millimeters result in no deterioration in the switching time characteristic and spread of the switch.

The groove 17, which is designed to lock the deformed portion of the aluminum U in metallic contact with the upper electrode, has a mouth 17a of smaller cross section than the base 17b of this groove so that the edge 17c framing the mouth of the groove overhangs the base and serves as a bar to lock any portion of the aluminum leg 9b deformed into this groove in place when the explosive force terminates. In this manner, undesired opening of the contact as a consequence of the magnetic-field-generated forces developed upon passage of current through the switch is prevented. Thus, the usefulness of the rapid-action switch of the present invention for highcurrent applications and in the presence of the forces generated by high-current flow and large current density is further augmented. To reduce the strain upon the anvil electrode 2 during triggering of switch closure, I found it advantageous to provide an upwardly open longitudinally extending groove 18 substantially coextensive with the mouth 17a of the groove 17 in the anvil electrode below the bottom leg of the aluminum member 9. Surprisingly, this groove increases the useful life of the anvil electrode quite substantially.

As noted generally above, the entire assembly is preferably under pressure, e.g., via the hydraulic piston-and-cylinder arrangement 19a and 19b. With switches of the aforementioned type, currents of 50 -l,200 kiloamps in main circuits under voltages of 60 kilovolts and frequencies of up to 300 kilohertz have been switched with switching times as short as 3.4 microseconds and a spread of less than 0.1 microseconds. The thickness of the U-shaped aluminum-sheet metal body 9 was 3 mm. in thickness and the foil 14 has a thickness of 0.2 mm. and was composed of polyethylene.

I claim:

1. a rapid-action switch for high-voltage and high-current switching operations, comprising:

a base electrode, and an incisor electrode spacedly juxtaposed with said base electrode and provided with at least one sharp edge;

a U-shaped aluminum body disposed between said electrodes and having generally flat legs extending parallel to each other and respectively juxtaposed with said base electrode and said incisor electrode with one of said legs in'electrical contact with said base electrode;

at least one insulating layer penetrable by said edge disposed between said incisor electrode and the other leg of said body; and

an actuating assembly between the legs of said body for driving the leg juxtaposed with said incisor electrode against the latter, said assembly comprising a pair of explosion-producing metal-foil electrode portions extending inwardly toward each other and a trigger-pulse source of relatively high voltage connected to said electrode portions at a relatively outer location, said metal foil electrode portions having monotonically widening cross sections outwardly therealong and away from one another.

2. The switch defined in claim 1 wherein said explosionproducing electrode portions are spaced from each other at respective inner ends and are at the same distance from both of said base and incisor electrodes and are insulated from said body except at said inner ends.

3. The switch defined in claim 2 wherein said metal-foil electrode portions have innermost and outermost cross sections in a ratio of substantially 1:10.

4. The switch defined in claim 2 wherein said metal-foil electrode portions are composed of a metal consisting predominantly of aluminum.

5. The switch defined in claim 2, further comprising a steel plate of high bending strength interposed between said metalfoil electrode portions and the leg of said body juxtaposed with said base electrode.

6. The switch defined in claim 2 wherein said incisor electrode is formed with at least one groove extending generally parallel to said metal-foil electrode portions and opening in the direction thereof at the mouth of a smaller cross section than the base of the groove, said edge being positioned within said groove.

7. The switch defined in claim 2 wherein said edge is formed by a system of mutually orthogonal prismatic ridges having edges extending along and perpendicular to the metal-foil electrode portions, at least one ridge extending transversely to the axis of the metal-foil electrode portions at a relatively narrow portion thereof and at least one ridge extending parallel to said axis along the relatively wide portion of each metal-foil electrode portion, the length of said edges corresponding to the width and length of the metal-foil electrode portion in the region thereof juxtaposed with said ridges.

8. The switch defined in claim 2 wherein said base electrode is formed with a groove of a width corresponding at least to that of said metal-foil electrode portions and extending therealong while opening in the direction of the metal-foil electrode portions.

9. The switch defined in claim 2 wherein said incisor and base electrodes are composed of a copper-beryllium alloy.

10. The switch defined in claim 2 wherein said incisor and base electrodes are formed with potential-controlling layers of metal or semiconductor along surfaces confronting said body.

11. The switch defined in claim 2 wherein said electrodes and said body are immersed in an insulating liquid or a weakconductivity electrolyte.

12. The switch defined in claim 2, further comprising means for blanketing said electrodes and said body in a voltagebreakdown-resisting gas at a pressure up to about 16 atmospheres.

13. The switch defined in claim 2, further comprising hydraulic means for urging said incisor and base electrodes toward one another.

14. The switch defined in claim 2, further comprising a load-inductance and a current source connected across said incisor electrode and base electrode so as to short circuit said load inductance upon metallic contact of said body with said incisor electrode. 

1. A rapid-action switch for high-voltage and high-current switching operations, comprising: a base electrode, and an incisor electrode spacedly juxtaposed with said base electrode and provided with at least one sharp edge; a U-shaped aluminum body disposed between said electrodes and having generally flat legs extending parallel to each other and respectively juxtaposed with said base electrode and said incisor electrode with one of said legs in electrical contact with said base electrode; at least one insulating layer penetrable by said edge disposed between said incisor electrode and the other leg of said body; and an actuating assembly between the legs of said body for driving the leg juxtaposed with said incisor electrode against the latter, said assembly comprising a pair of explosion-producing metal-foil electrode portions extending inwardly toward each other and a trigger-pulse source of relatively high voltage connected to said electrode portions at a relatively outer location, said metal foil electrode portions having monotonically widening cross sections outwardly therealong and away from one another.
 2. The switch defined in claim 1 wherein said explosion-producing electrode portions are spaced from each other at respective inner ends and are at the same distance from both of said base and incisor electrodes and are insulated from said body except at said inner ends.
 3. The switch defined in claim 2 wherein said metal-foil electrode portions have innermost and outermost cross sections in a ratio of substantially 1:10.
 4. The switch defined in claim 2 wherein said metal-foil electrode portions are composed of a metal consisting predominantly of aluminum.
 5. The switch defined in claim 2, further comprising a steel plate of high bending strength interposed between said metal-foil electrode portions and the leg of said body juxtaposed with said base electrode.
 6. The switch defined in claim 2 wherein said incisor electrode is formed with at least one groove extending generally parallel to said metal-foil electrode portions and opening in the direction thereof at the mouth of a smaller cross section than the base of the groove, said edge being positioned within said groove.
 7. The switch defined in claim 2 wherein said edge is formed by a system of mutually orthogonal prismatic ridges having edges extending along and perpendicular to the metal-foil electrode portions, at least one ridge extending transversely to the axis of the metal-foil electrode portions at a relatively narrow portion thereof and at least one ridge extending parallel to said axis along the relatively wide portion of each metal-foil electrode portion, the length of said edges corresponding to the width and length of the metal-foil electrode portion in the region thereof juxtaposed with said ridges.
 8. The switch defined in claim 2 wherein said base electrode is formed with a groove of a width corresponding at least to that of said metal-foil electrode portions and extending therealong while opening in the direction of the metal-foil electrode portions.
 9. The switch defined in claim 2 wherein said incisor and base electrodes are composed of a copper-beryllium alloy.
 10. The switch defined in claim 2 wherein said incisor and base electrodes are formed with potential-controlling layers of metal or semiconductor along surfaces confronting said body.
 11. The switch defined in claim 2 wherein said electrodes and said body are immersed in an insulating liquid or a weak-conductivity electrolyte.
 12. The switch defined in claim 2, further comprising means for blanketing said electrodes and said body in a voltage-breakdown-resisting gas at a pressure up to about 16 atmospheres.
 13. The switch defined in claim 2, further comprising hydraulic means for urging said incisor and base electrodes toward one another.
 14. The switch defined in claim 2, further comprising a load-inductance and a current source connected across said incisor electrode and base electrode so as to short circuit said load inductance upon metallic contact of said body with said incisor electrode. 